For example, an object detection device such as a laser radar for vehicle mounting includes a projection optical system that projects light; a light receiving optical system that receives light projected and reflected off a target; and the like.
As disclosed in JP H07-183621 A, JP 2014-32149 A, JP 2014-235075 A, JP 2015-137951 A, JP 2004-146720 A, JP H09-232677 A, JP 2014-154851 A, and JP 2016-115767 A, a projection optical system includes laser diodes which are light sources and optical components such as a light projecting lens that adjusts the spread of light emitted from the laser diodes. A light receiving optical system includes a light receiving element that receives light projected from the projection optical system and reflected off a target, and the like.
In addition, as disclosed in JP 2014-32149 A, JP 2014-235075 A, and JP 2015-137951 A, there are also a projection optical system and a light receiving optical system that include an optical deflector that deflects light having passed through a light projecting lens and projects the deflected light onto a target, and deflects light reflected from the target and allows the deflected light to enter a light receiving element.
An object detection device determines whether there is a target, based on a light reception signal outputted from a light receiving element. In addition, there is also an object detection device that detects a distance from the object detection device to a target based on, for example, a period of time from when laser diodes emit light until a light receiving element receives light reflected from a target.
For example, to expand a target detection range or to improve detection accuracy, plural laser diodes are used as light sources. There is also a module in which a plurality of laser diodes is arranged in one direction (e.g., JP H07-183621 A, JP 2015-137951 A, JP 2004-146720 A, JP H09-232677 A, JP 2014-154851 A, and JP 2016-115767 A). In addition, there is also one in which such plural laser diode modules are stacked on top of each other in one direction (e.g., JP 2004-146720 A, JP 2014-154851 A, and JP 2016-115767 A). Furthermore, there is also a laser diode module including a cooling structure to cool heat generated from laser diodes (e.g., JP 2004-146720 A, JP H09-232677 A, JP 2014-154851 A, and JP 2016-115767 A).
In JP 2014-32149 A, JP 2014-235075 A, and JP 2015-137951 A, plural laser diodes are disposed side by side in an up-down direction (e.g., an up-down direction of a vehicle body) perpendicular to a direction in which an optical deflector deflects and scans light.
Some laser diodes have a characteristic in which emitted light spreads out at a narrow angle in one direction and spreads out at a wide angle in a direction perpendicular to the one direction within a plane perpendicular to an optical axis of the emitted light (e.g., JP 2014-32149 A).
When plural laser diodes or plural laser diode modules are used as light sources, if the laser diodes or the laser diode modules are disposed in a row in one direction such as an up-down direction, a projection optical system or an object detection device increases in size in the one direction.